Is there a way to export each rendered layer as its own image?
Use a file output node and save as openEXR multilayer:



The EXR multilayer format will allow you to save multiple render layers and passes in a single file.

The EXR format is the best way to preserve the integrity of your render layers, as it will keep them linearized and without any the constraints of display referred images (in other words you can keep values that exceed the 0-1 scale).

Saving as OpenEXR multilayer will help you also if you are compositing using Z-pass information.

You can create as many channels as you need.



See these links for more details: https://blender.stackexchange.com/a/18406/1853

Note: To open this kind of file in old versions of photoshop there is a plugin you can download from http://www.openexr.com/